Sand-dredging vessel



Nov. 6, 1928.

L. D. SMITH SAND DREDGING VESSEL Filed June 1, 1926 2 Sheets-Sheet lNov. 6, 1928.

1,690,380 L. D. SMITH SAND DREDGING VESSEL 2 Sheets-Sheet 2 Filed June1, 1926 fizz/677161) Leaf/zen: D Jm 65%,

y Wag Q Patented Nov. 6, 1928.

UNITED STATES PATENT OFFICE. T

LEATHEM 1). SMITH, OF STURGEON BAY, WISCONSIN.

SAND-DREDGING VESSEL.

Application filed June 1,

der conditions which will render the operation not only economical incost but safe from from the hazard of overloading with water, as well asthe hazard of shifting cargo when loading is done or the cargo is beingtransported in rough or unprotected waters. It has heretofore been thepractice to pump sand or other material responsive to suction dredging,and pass the same, with a relatively large volume of water serving as avehicle, through a flume provided at intervals with screens throughwhich the water and finer material are allowed to pass, and to deliverthe material with all of its vehicular water into the hold of thevessel, until by the accumulation of settled solid matter, the excess ofwater is caused to rise through the hatches and escape over the deck.But this method of loading necessitates a hull construction in which thegross capacity is sacrificed by the placing of bulkheads in maintainingbuoyancy space and restricting the actual carrying capacity todimensions which will insure remaining afloat when the cargo space isfilled with water; moreover, the material goes into the hold in such ahigh state of fluidity that stability will be destroyed in rough water.One remedy proposed for this difliculty is to provide drainage space forthe excessive volume of water admitted to the hold, and to constantlypump the water from the bilge in which it drains, but the quantity ofwater re quired to be pumped adds great expense to the operating cost.

The present invention proceeds upon the principle of automaticallydewatering the pumped material at a stage in the operation which liesbeyond the'screening point, but in advance of theadmission of the solidmate rial to the hold, this step being preferably performed by theoverflow method of dewatering, carried on in a large number ofdewatering units, preferably one for each screen, so that materialadmitted to the hold contains only the water occupying the voids betweenthe grains or subdivisions of the ma- 1926. Serial No. 112,773.

terials, and while sufiiciently plastic to readily accommodate itself tohold spaces to which it may be delivered, has no such degree of fluid-1ty as would endanger the stability of the ship by cargo-shifting inrough water; moreover, the hold itself is provided with means, such, forinstance, as a central longitudinal barrier which retains the cargo inposition on opposite sides of the keel, or a'plurality of such barrierswhich subdivide the cargo space into several longitudinal spaces; andthese barriers are preferably constructed so that they serve as drainagespaces for that portion of the water which occupies the voids betweenthe particles of subdivided material i and which gradually gravitatesfrom the mass. The barriers may even be designed to serve as a means ofaccess to the cargo, for instance, by making them in the form of tunnelsof sufficient capacity to admit unloading apparatus, and having cantboards or the like which cause the material to gradually feed to suchunloading tunnels.

An important feature of the invention consists in having the dewateringunits which receive the water and material from the screens, so designedthat by regulating escape valves inthe dewatering hoppers, the material,with its remanent water, will flow from the hoppers only at apredetermined rate,and Whenever the feed of material and water from thescreen exceeds the rate of escape, the accumu lation will build uparound the spout leading from the screen and check the inflow of furthermaterial at that particular unit, thus causing the material to pass tosuccessive units until the obstructed unit automatically clears itself.This arrangement of controll'able valve dewatering units alsoaifords'con- 'venient means through which to insure distribution of thelading throughout the hold, it being merely necessary to restrict theopening or wholly close the valves in locations where an excess ofloading becomes manifest,

in order to reduce loading at such points until the vessel regains aneven keel by the process,

substantially dewatered state, and, therefore,

sufliciently immobile to prevent trimming the cargo by the natural flowof the material within thehold. 7

Located beneath the branches 4 of the fiume' and at regular intervalsalongthe deck on either side of the center line of the hulh'are"de'watering hoppers 5, each of which is adapted to be fed through aspout 6 from a screen 7 in the bbttom'of the flume,-and

each'of whichis designedto discharge into the hold of the vessel througha port 8. In this way, the hoppers 5' will receive, along WithsufiicientWater to insure fluidity, such portions of the material' pumped into thefiume 4 as is intended to" be passed by the screens 7,.the ta ilings' orcoarser material ultimately escaping at 9." 'Bu't material onte'ring ahopper 5 is restrained in its escape therefrom by means of a suitablevalve, for

instance, a hemispherical valve 10 suspended by a flexible connector 11from, the winding shaft 12 which'it reaches by way of the pulley 13, andin this way, each hopper will be kept normally filled with screenedmaterial to such a level as will cause surplus water to overfiow'thebrim of'tliehopper while the materialis yet above deck andthus escapeoverboard by gravity and without the expen'se of pumping it,'jas wouldbe thecase if the water could freely enter the holdalong with thematerial saved. "The spoutS beneathea'ch screen 7 terminatesin suchclose proximity to the horizontal plane of the brim of the hopper 5 thatif the material flows through the screen at a greater rate than that atwhich it gravitates through the throat, which isconstrictedby the valve'10, the materialwill pile up andseal the lower end of thejspoutr bythenatuial angle of repose w sought 1 by the material, notwithstandingits contained water, andin this way the feed of material through theparticular-screen which ZlSf thus temporarily blocked, will beinterrupted until the hopper 5fautomatically clears "itself sufficientlyto reinduce flow through the screen.

blocked, the material in the mine passes over hen a screen is thus ititoscreens'bcyond, and while the capacity of the flume and the pumpwhichfeeds it, as

W well as the inclination ofthe flumeand other elements of design, willbe suilicient to "supply all of'the screens simultaneously, thedescribed method ofregulatingthe flow through eachparticular screen, ata rate predeter' mined by the adjustment of its valve 10, will serve toinsure distribution of the cargo. Moreover, if it be found that thevessel is listing by reason of excessive accumulation on one siderelatively to the other, or is down at the bow or stern, the operatorwill regulate valve openings or close the valves altogether of suchnumbers of screens as will be necessary to correct the inaccuracy ofdistri bution.

The material that enters the hold of the vessel will, of course, havetrapped in it a proportion of water roughly mcasurcd by the capacity ofthe voids between the particles of the material, and ordinarily thematerial will reach the hold of the vessel in a soupy or mushycondition, which will adversely affect equilibrium of the vessel in caseof roll-' ingin rough water, and to avoid this contingency, one or more.barriers 14 are erected within the hold. and extended from end to aswill resist shifting of the load, at least to a degree which will leavethe cargo relatively solid and immobile. In the drawings two suchbarriers are shown; and to adapt them to serve as escape channels forsuch water as issues from the loaded material by gravitatiomand deliversuch water to the bilge pump 19, said barriers'arc in the form oftunnels with deflecting top walls'15 and screened side walls 16, and thebottom of the cargo space is defined by cant boards 17 and 18 whichcause the water to flow into the tunnels. The tunnels 1d will preferablybe of suflicient capacity to admit operatives as well as automatic orother unloading apparatusor implements, and their screens 16 will beremovable so that after-it becomes safe to do so, the cargo may beallowed to gravitate into the tunnelsand thusrendered accessible forunloading. v

A loading system for dredged materials as herein described is veryeconomical to operate by reason of the use of gravity for bothpreliminary and ultimate dewatering, as well as'for feeding the materialtoward a common unloading tunnel. The cargo is made safe againstshiftingso long as it is in'amushy or mobile condition, by reason ofcontained water, and as long thereafter as maybe found necessary underextreme weatherconditions; A ship may be loaded to very much greatercapacity by reason of separation of the greater portion of the waterbefore the material enters the hold, and control of the load ing may becarried on with: regularity and economy by regulation of escape of thematerial fromthe hoppers in which it is received from the screen. I

1. A floating vessel for dredging and transporting material such as asand, constructed with a storage hold lordredged ma until thewater canfurther escape by gravity tau terial and having mounted upon it meansfor pumping material, together with :1 vehicular constituent of water,from an overboard position and delivering such material to a positionabove the storage hold, a dewatering hopper also located above thestorage hold in position to receive the material so delivered anddischarge its contained water overboard, means for delaying escape ofthe material from the hopper until dewatering has proceeded to a desireddegree. and means for delivering dewatered material from said hopper tothe hold of the vessel.

2. A floating vessel for dredging and transporting material such assand, constructed with a storage hold for dredged material, and havingmounted upon it means for pumping thematerial from an overboard positionand delivering it with a vehicular constituent of water to a point abovethe storage hold, means receiving the material so delivered andconveying it to a plurality of points of release, which are also abovethe storage hold, dewatering means receiving the material escaping atthe several points of release and confining such material in positionswhich are above the storage hold and from which water escaping from thematerial may flow overboard by gravity, means delaying escape ofmaterial from said dewatering means until a desired proportion of itscontained water has escaped, and a plurality of discharge spoutsdirecting material from the dewatering means to distributed pointswithin the storage hold.

3, A floating vessel for dredging and transporting material such assand, said vessel being constructed with a storage hold and havingmounted upon it means for pumping the material, along with a vehicularconstituent of water, from an overboard position to a position which isabove the storage hold, a flume located above the storage hold inposition to receive the material and water pumped, said flume beingconstructed todeliver a restricted portion of the material and water, adewatering hopper also located above the storagehold, in position toreceive a restricted portion of material and water delivered by theflume and to release a desired proportion of the water for dischargeoverboard by gravity, means for delaying escape of the material from thehopper until the desired proportion of its contained water has escaped,and means delivering the dewatered material from said hopper to thestorage hold.

4. A floating vessel for dredging and transporting material such assand, said vessel being constructed with a storagehold and havingmounted upon it means for pumping the material, along with a vehicularconstituent of water, from an overboard position to a position which isabove the storage hold, a fiume located above the storage hold inposition to receive the material and water pumped, said flume beingconstructed to deliver a restricted portion of the material and water, adcwatering hopper also located above the storage hold, in position toreceive a restricted portion of material and water delivered by theflume and to release a desired proportion of the water for dischargeoverboard by gravity, means'directing the flow of material from theflume to the dewatering hopper constructed to arrest flow of materialfrom the fluine when the accumulation in the hopper reaches apredetermined level, means for delaying escape of the material from thehopper until the desired proportion of its contained water has escaped,and means delivering the dewatered material from said hopper to thestorage hold.

5. A floating vessel for dredging and transporting material such assand, constructed with a storage hold for dredged material and havingmounted upon it means for pumping material, together with a vehicularconstituent of water, from an overboard position and delivering suchmaterial to a position above the storage hold, a dewatering hopper alsolocated above the storage hold in position to receive the mate-rial sodelivered and discharge its contained water overboard, means tordelaying escape of the material from the hopper until dewatering hasproceeded to a desired degree, and means for delivering dewateredmaterial from said hopper to the hold of the vessel; the last-namedmeans being provided with an adjustable valve permitting flow ofmaterial from the hopper only at a predetermined rate.

6. A floating vessel for dredging material such as sand, said vesselbeing constructed with a storage hold and having mounted upon it meansfor pumping from an overboard position, to a position above the storagehold, material accompanied by a vehicular constituent of water, a flumeabove the storage hold in position to receive the material and waterpumped, said flume being constructed with a plurality of screeneddischarge openings over which the material selectively flows and whichpermit the escape of water with restricted portions of the material,dewatering hoppers also above the storage hold located beneath therespective discharge openings of the flume and permitting the escapeofdesired-portions of the water overboard by gravity, delivery meanscarried by the respective hoppers for directing the material to thestorage hold, and independently adjustable valves for the respectivedelivery means adapted to retard escape of the material from the hopperto the hold until a desired proportion of the water has escaped from thematerial;

7. A floating vessel for dredging and transporting material such assand, said vessel being constructed with a storage hold and having insaid storage hold a fore and aft tunnel and a vehicular constituent ofWater from an overboard position to a position above the storage hold,means also above the storage hold receiving the pumped material andwater, fluxnes branching from said receiving means and extending foreand aft of the vessel above the storage hold and permitting the flow ofmaterial and water through them, lurality a l of means distributed alongthe lengtli of each flume for releasing water with restricted portionsof lmaterial, dewatering hoppers also above the storage hold, inposition to release water from the material and permit it to escapeoverboard by gravity, said hoppers being located beneath the respectivereleasing means of the flames, and means directing material from therespective hoppers to distributed points on opposite sides of anddistributed along the length of the tunnel within the hold.

Signed at Sturgeon Bay, \Visconsin, this 25th day of May, 1926.

LEATHEM D. SMITH.

